INVESTIGATION OF THE FATIGUE LIFE FOR THE AA7001-T6 AT DIFFERENT TEMPERATURES UNDER VARIABLE LOADING

Abstract

ABSTRACT Aluminum alloys are being utilized increasingly often in the automotive, transportation, marine, and aerospace industries. Due to their superior strength, resistance to wear, and fatigue resistance, The main goal of this study is to obtain experimentally the fatigue life of the selected alloy under different conditions fatigue life under elevated temperatures and variable loading the mechanical characteristics of AA7001-T6, including ultimate tensile stress (UTS), yield stress (YS), Young modulus (E), and ductility, the reduction percentages were recorded to be 37%, 37.2%, and 24% respectively while the ductility increased by 28.57%. Fatigue interaction have a large effect on fatigue strength and life. The endurance fatigue limit was recorded to 208 Mpa at 2 about an 11.5% reduction occurred. Shot peening reduced the percentage to 32.2% and 36.7%, respectively. Shot peening treatment increased the improved fatigue limit at 330 °C from 217 MPa to 229 MPa, 5.24% improvement. The endurance fatigue limit (fatigue strength) was found to be 229 MPa at RT, but it increased to 237 MPa as a result of SP 3.37%. The cumulative fatigue damage under rotating bending loading and the stress ratio R = -1 were calculated. The experiments were carried out at (25°C), (330°C), and (SP+330°C), respectively. Use a modified damage stress model that has been developed to account for damage at different load levels to forecast the fatigue life under high temperatures. the output of the model was compared to experimental results as well as to an output from the fatigue damage model that was used to determine the greatest damage (Miner's rule). The results of the two models one for low-high loading and the other for high-low loading were suitable for extending fatigue life